为什么 chrome 尊重某些资源的缓存控制标头，但不尊重其他资源？答案

【问题标题】：Why does chrome respect the cache-control header for some resources, but does not for others?为什么 chrome 尊重某些资源的缓存控制标头，但不尊重其他资源？
【发布时间】：2014-01-16 02:52:03
【问题描述】：

我有一个具有以下设置的 AJAX 应用程序：

动态内容由来自 localhost:8000 的 node.js 服务器提供
静态内容由来自 localhost:8080 的码头服务器提供服务

动态内容有两种：

基于 SQL 查询结果的真正动态内容
组合处理程序的结果，用于连接文件。实际上这个内容永远不会改变，所以它也可以被认为是静态的。

我执行以下步骤：

清除 chrome 浏览缓存（设置 -> 清除浏览数据 ... -> 清空缓存）
刷新应用程序
刷新应用程序

静态内容以及组合处理程序生成的内容都具有 cache-control 标头，后者也具有 expires 标头。

我预计第一次刷新会加载所有资源，但第二次只是真正的动态内容。即使这样，也不会返回任何内容，因为没有修改任何内容。

实际上，浏览器应该加载更多资源。

请在下面找到第一次刷新后浏览器发出的请求的摘要（组合 url 很长，所以为了清楚起见，我将它们截断了）：

#   Result  Protocol    Host            URL                                                                                             Body    Caching                                                         Content-Type                            Process
1   200     HTTP        localhost:8000  /                                                                                               14,348                                                                  text/html; charset=utf-8                chrome:3852         
2   200     HTTP        localhost:8000  /combo?yui/cssreset/cssreset-min.css&yui/cssfonts/cssfonts-min.css                              638     public,max-age=31536000; Expires: Fri, 16 Jan 2015 02:15:49 GMT text/css; charset=utf-8                 chrome:3852         
3   200     HTTP        localhost:8080  /if/admin.min.css                                                                               22,176  public,max-age=31536000                                         text/css                                chrome:3852         
4   200     HTTP        localhost:8080  /yui/yui/yui-min.js                                                                             25,586  public,max-age=31536000                                         application/javascript                  chrome:3852         
5   200     HTTP        localhost:8080  /if/admin.min.js                                                                                37,889  public,max-age=31536000                                         application/javascript                  chrome:3852         
6   200     HTTP        localhost:8000  /combo?yui/cssgrids/cssgrids-min.css&yui/widget-base/assets/skins/sam/widget-base.css&...       6,223   public,max-age=31536000; Expires: Fri, 16 Jan 2015 02:15:49 GMT text/css; charset=utf-8                 chrome:3852         
7   200     HTTP        localhost:8000  /combo?yui/oop/oop-min.js&yui/attribute-core/attribute-core-min.js&...                          97,019  public,max-age=31536000; Expires: Fri, 16 Jan 2015 02:15:49 GMT application/javascript; charset=utf-8   chrome:3852         
8   200     HTTP        localhost:8000  /combo?yui/dataschema-json/dataschema-json-min.js&yui/dataschema-xml/dataschema-xml-min.js&...  46,248  public,max-age=31536000; Expires: Fri, 16 Jan 2015 02:15:50 GMT application/javascript; charset=utf-8   chrome:3852         
9   200     HTTP        localhost:8000  /combo?yui-gallery/gallery-querybuilder/assets/skins/sam/gallery-querybuilder.css&...           872     public,max-age=31536000; Expires: Fri, 16 Jan 2015 02:15:51 GMT text/css; charset=utf-8                 chrome:3852         
10  200     HTTP        localhost:8000  /combo?yui-gallery/gallery-formmgr/gallery-formmgr-min.js&...                                   4,627   public,max-age=31536000; Expires: Fri, 16 Jan 2015 02:15:51 GMT application/javascript; charset=utf-8   chrome:3852         
11  200     HTTP        localhost:8000  /combo?yui-gallery/gallery-node-optimizations/gallery-node-optimizations-min.js&...             2,269   public,max-age=31536000; Expires: Fri, 16 Jan 2015 02:15:51 GMT application/javascript; charset=utf-8   chrome:3852         
12  200     HTTP        localhost:8000  /combo?yui/substitute/substitute-min.js                                                         1,006   public,max-age=31536000; Expires: Fri, 16 Jan 2015 02:15:51 GMT application/javascript; charset=utf-8   chrome:3852         
13  200     HTTP        localhost:8000  /api/context                                                                                    81,238                                                                  application/json; charset=utf-8         chrome:3852         
14  200     HTTP        localhost:8080  /yui/assets/skins/sam/sprite.png                                                                2,913   public,max-age=31536000                                         image/png                               chrome:3852         
15  200     HTTP        localhost:8080  /yui/node-menunav/assets/skins/sam/horizontal-menu-submenu-indicator.png                        157     public,max-age=31536000                                         image/png                               chrome:3852

注意事项：

请求 1 和 13 产生真正的动态内容 - 1 是呈现为 html 的翡翠模板，而 13 是 SQL 查询的结果
请求 3、4、5、14 和 15 产生静态内容（注意端口号为 8080）
其余请求是组合请求 - 法律上是动态的，但事实上是静态的。

现在这是第二次刷新后该摘要的样子：

#   Result  Protocol    Host            URL                                                                                             Body    Caching Content-Type                                                Process
1   304     HTTP        localhost:8000  /                                                                                               0                                                                           chrome:3852         
2   304     HTTP        localhost:8000  /combo?yui/cssreset/cssreset-min.css&yui/cssfonts/cssfonts-min.css                              0       public,max-age=31536000; Expires: Fri, 16 Jan 2015 02:38:55 GMT     chrome:3852         
3   304     HTTP        localhost:8080  /if/admin.min.css                                                                               0                                                                           chrome:3852         
4   304     HTTP        localhost:8080  /yui/yui/yui-min.js                                                                             0                                                                           chrome:3852         
5   304     HTTP        localhost:8080  /if/admin.min.js                                                                                0                                                                           chrome:3852         
6   304     HTTP        localhost:8000  /combo?yui/cssgrids/cssgrids-min.css&yui/widget-base/assets/skins/sam/widget-base.css&...       0       public,max-age=31536000; Expires: Fri, 16 Jan 2015 02:38:55 GMT     chrome:3852         
7   304     HTTP        localhost:8000  /combo?yui/oop/oop-min.js&yui/attribute-core/attribute-core-min.js&...                          0       public,max-age=31536000; Expires: Fri, 16 Jan 2015 02:38:55 GMT     chrome:3852         
8   304     HTTP        localhost:8000  /combo?yui/dataschema-json/dataschema-json-min.js&yui/dataschema-xml/dataschema-xml-min.js&...  0       public,max-age=31536000; Expires: Fri, 16 Jan 2015 02:38:56 GMT     chrome:3852         
9   304     HTTP        localhost:8000  /api/context                                                                                    0                                                                           chrome:3852

请注意，第一个摘要中的请求 9 - 12,14 和 15 的 URL 在第二个摘要中不存在 - 浏览器会缓存它们。但是，为什么浏览器不缓存请求 2 - 8（来自第一个摘要），这些请求似乎与缓存的质量相同？

附录 A

请在下面找到第一次刷新后所有请求和响应的完整标题（我使用了一个新会话，因此日期与上面给出的简短摘要不同）：

GET / HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Cache-Control: max-age=0
Authorization: Basic YWRtaW46MTIz
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 200 OK
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,PUT,POST,DELETE,OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, Content-Length, X-Requested-With
Vary: Accept-Encoding
Content-Type: text/html; charset=utf-8
ETag: "-1836563736"
Content-Encoding: gzip
Date: Thu, 16 Jan 2014 02:53:55 GMT
Connection: keep-alive
Transfer-Encoding: chunked

---
GET /combo?yui/cssreset/cssreset-min.css&yui/cssfonts/cssfonts-min.css HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Cache-Control: max-age=0
Authorization: Basic YWRtaW46MTIz
Accept: text/css,*/*;q=0.1
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 200 OK
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,PUT,POST,DELETE,OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, Content-Length, X-Requested-With
Vary: Accept-Encoding
Last-Modified: Tue, 23 Apr 2013 23:46:18 GMT
Cache-Control: public,max-age=31536000
Expires: Fri, 16 Jan 2015 02:53:55 GMT
Content-Type: text/css; charset=utf-8
ETag: "-1463284566"
Content-Encoding: gzip
Date: Thu, 16 Jan 2014 02:53:55 GMT
Connection: keep-alive
Transfer-Encoding: chunked

---
GET /yui/yui/yui-min.js HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Cache-Control: max-age=0
Accept: */*
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 200 OK
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Type: application/javascript
Accept-Ranges: bytes
Cache-Control: public,max-age=31536000
Last-Modified: Tue, 14 Jan 2014 11:59:00 GMT
ETag: W/"4gIxoOsipQY4gIw4Hu8s3Y"
Content-Length: 25586
Server: Jetty(9.1.0.v20131115)

---
GET /if/admin.min.css HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Cache-Control: max-age=0
Accept: text/css,*/*;q=0.1
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 200 OK
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Type: text/css
Accept-Ranges: bytes
Cache-Control: public,max-age=31536000
Last-Modified: Tue, 14 Jan 2014 11:59:00 GMT
ETag: W/"vSW0rAEe/b8vSW17JGA3h4"
Content-Length: 22176
Server: Jetty(9.1.0.v20131115)

---
GET /if/admin.min.js HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Cache-Control: max-age=0
Accept: */*
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 200 OK
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Type: application/javascript
Accept-Ranges: bytes
Cache-Control: public,max-age=31536000
Last-Modified: Tue, 14 Jan 2014 11:59:00 GMT
ETag: W/"7VPNTHzTc387VPMDOxNk7k"
Content-Length: 37889
Server: Jetty(9.1.0.v20131115)

---
GET /combo?yui/cssgrids/cssgrids-min.css&yui/widget-base/assets/skins/sam/widget-base.css&... HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Cache-Control: max-age=0
Authorization: Basic YWRtaW46MTIz
Accept: text/css,*/*;q=0.1
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 200 OK
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,PUT,POST,DELETE,OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, Content-Length, X-Requested-With
Vary: Accept-Encoding
Last-Modified: Tue, 23 Apr 2013 23:46:22 GMT
Cache-Control: public,max-age=31536000
Expires: Fri, 16 Jan 2015 02:53:55 GMT
Content-Type: text/css; charset=utf-8
ETag: "1986623550"
Content-Encoding: gzip
Date: Thu, 16 Jan 2014 02:53:55 GMT
Connection: keep-alive
Transfer-Encoding: chunked

---
GET /combo?yui/oop/oop-min.js&yui/attribute-core/attribute-core-min.js&... HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Cache-Control: max-age=0
Authorization: Basic YWRtaW46MTIz
Accept: */*
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 200 OK
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,PUT,POST,DELETE,OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, Content-Length, X-Requested-With
Vary: Accept-Encoding
Last-Modified: Thu, 02 May 2013 22:59:53 GMT
Cache-Control: public,max-age=31536000
Expires: Fri, 16 Jan 2015 02:53:55 GMT
Content-Type: application/javascript; charset=utf-8
ETag: "1918884200"
Content-Encoding: gzip
Date: Thu, 16 Jan 2014 02:53:55 GMT
Connection: keep-alive
Transfer-Encoding: chunked

---
GET /combo?yui/dataschema-json/dataschema-json-min.js&yui/dataschema-xml/dataschema-xml-min.js&... HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Cache-Control: max-age=0
Authorization: Basic YWRtaW46MTIz
Accept: */*
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 200 OK
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,PUT,POST,DELETE,OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, Content-Length, X-Requested-With
Vary: Accept-Encoding
Last-Modified: Tue, 23 Apr 2013 23:46:24 GMT
Cache-Control: public,max-age=31536000
Expires: Fri, 16 Jan 2015 02:53:56 GMT
Content-Type: application/javascript; charset=utf-8
ETag: "1381642784"
Content-Encoding: gzip
Date: Thu, 16 Jan 2014 02:53:56 GMT
Connection: keep-alive
Transfer-Encoding: chunked

---
GET /combo?yui-gallery/gallery-querybuilder/assets/skins/sam/gallery-querybuilder.css&... HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Authorization: Basic YWRtaW46MTIz
Accept: text/css,*/*;q=0.1
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 200 OK
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,PUT,POST,DELETE,OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, Content-Length, X-Requested-With
Vary: Accept-Encoding
Last-Modified: Thu, 02 May 2013 22:59:53 GMT
Cache-Control: public,max-age=31536000
Expires: Fri, 16 Jan 2015 02:53:56 GMT
Content-Type: text/css; charset=utf-8
Content-Length: 872
Date: Thu, 16 Jan 2014 02:53:56 GMT
Connection: keep-alive

---
GET /combo?yui-gallery/gallery-formmgr/gallery-formmgr-min.js&yui-gallery/gallery-overlay-extras/gallery-overlay-extras-min.js HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Authorization: Basic YWRtaW46MTIz
Accept: */*
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 200 OK
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,PUT,POST,DELETE,OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, Content-Length, X-Requested-With
Vary: Accept-Encoding
Last-Modified: Thu, 02 May 2013 22:59:53 GMT
Cache-Control: public,max-age=31536000
Expires: Fri, 16 Jan 2015 02:53:56 GMT
Content-Type: application/javascript; charset=utf-8
ETag: "264489472"
Content-Encoding: gzip
Date: Thu, 16 Jan 2014 02:53:56 GMT
Connection: keep-alive
Transfer-Encoding: chunked

---
GET /combo?yui-gallery/gallery-node-optimizations/gallery-node-optimizations-min.js&... HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Authorization: Basic YWRtaW46MTIz
Accept: */*
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 200 OK
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,PUT,POST,DELETE,OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, Content-Length, X-Requested-With
Vary: Accept-Encoding
Last-Modified: Thu, 02 May 2013 22:59:53 GMT
Cache-Control: public,max-age=31536000
Expires: Fri, 16 Jan 2015 02:53:56 GMT
Content-Type: application/javascript; charset=utf-8
ETag: "946735146"
Content-Encoding: gzip
Date: Thu, 16 Jan 2014 02:53:56 GMT
Connection: keep-alive
Transfer-Encoding: chunked

---
GET /combo?yui/substitute/substitute-min.js HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Authorization: Basic YWRtaW46MTIz
Accept: */*
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 200 OK
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,PUT,POST,DELETE,OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, Content-Length, X-Requested-With
Vary: Accept-Encoding
Last-Modified: Tue, 23 Apr 2013 23:46:22 GMT
Cache-Control: public,max-age=31536000
Expires: Fri, 16 Jan 2015 02:53:56 GMT
Content-Type: application/javascript; charset=utf-8
Content-Length: 1006
Date: Thu, 16 Jan 2014 02:53:56 GMT
Connection: keep-alive

---
GET /api/context HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Authorization: Basic YWRtaW46MTIz
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
X-Requested-With: XMLHttpRequest
Accept: */*
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 200 OK
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,PUT,POST,DELETE,OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, Content-Length, X-Requested-With
Vary: Accept-Encoding
Content-Type: application/json; charset=utf-8
ETag: "1217632044"
Content-Encoding: gzip
Date: Thu, 16 Jan 2014 02:53:56 GMT
Connection: keep-alive
Transfer-Encoding: chunked

---
GET /yui/assets/skins/sam/sprite.png HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Accept: image/webp,*/*;q=0.8
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 200 OK
Accept-Ranges: bytes
Cache-Control: public,max-age=31536000
Content-Type: image/png
Last-Modified: Tue, 23 Apr 2013 23:46:18 GMT
ETag: W/"oHo6+Hf6zcMoHo7xE6wr7I"
Content-Length: 2913
Server: Jetty(9.1.0.v20131115)

---
GET /yui/node-menunav/assets/skins/sam/horizontal-menu-submenu-indicator.png HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Accept: image/webp,*/*;q=0.8
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 200 OK
Accept-Ranges: bytes
Cache-Control: public,max-age=31536000
Content-Type: image/png
Last-Modified: Tue, 23 Apr 2013 23:46:20 GMT
ETag: W/"jvhF7Fl3QdUjvhE0GA9Mag"
Content-Length: 157
Server: Jetty(9.1.0.v20131115)

---

附录 B

请在下面找到第二次刷新后所有请求和响应的完整标题（我使用了一个新会话，因此日期与上面给出的简短摘要不同）：

GET / HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Cache-Control: max-age=0
Authorization: Basic YWRtaW46MTIz
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8
If-None-Match: "-1836563736"

HTTP/1.1 304 Not Modified
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,PUT,POST,DELETE,OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, Content-Length, X-Requested-With
Vary: Accept-Encoding
ETag: "-1836563736"
Date: Thu, 16 Jan 2014 03:03:44 GMT
Connection: keep-alive

---
GET /combo?yui/cssreset/cssreset-min.css&yui/cssfonts/cssfonts-min.css HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Cache-Control: max-age=0
Authorization: Basic YWRtaW46MTIz
Accept: text/css,*/*;q=0.1
If-None-Match: "-1463284566"
If-Modified-Since: Tue, 23 Apr 2013 23:46:18 GMT
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 304 Not Modified
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,PUT,POST,DELETE,OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, Content-Length, X-Requested-With
Vary: Accept-Encoding
Last-Modified: Tue, 23 Apr 2013 23:46:18 GMT
Cache-Control: public,max-age=31536000
Expires: Fri, 16 Jan 2015 03:03:44 GMT
ETag: "-1463284566"
Date: Thu, 16 Jan 2014 03:03:44 GMT
Connection: keep-alive

---
GET /if/admin.min.css HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Cache-Control: max-age=0
Accept: text/css,*/*;q=0.1
If-None-Match: W/"vSW0rAEe/b8vSW17JGA3h4"
If-Modified-Since: Tue, 14 Jan 2014 11:59:00 GMT
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 304 Not Modified
Vary: Accept-Encoding
ETag: W/"vSW0rAEe/b8vSW17JGA3h4"
Server: Jetty(9.1.0.v20131115)

---
GET /yui/yui/yui-min.js HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Cache-Control: max-age=0
Accept: */*
If-None-Match: W/"4gIxoOsipQY4gIw4Hu8s3Y"
If-Modified-Since: Tue, 14 Jan 2014 11:59:00 GMT
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 304 Not Modified
Vary: Accept-Encoding
ETag: W/"4gIxoOsipQY4gIw4Hu8s3Y"
Server: Jetty(9.1.0.v20131115)

---
GET /if/admin.min.js HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Cache-Control: max-age=0
Accept: */*
If-None-Match: W/"7VPNTHzTc387VPMDOxNk7k"
If-Modified-Since: Tue, 14 Jan 2014 11:59:00 GMT
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 304 Not Modified
Vary: Accept-Encoding
ETag: W/"7VPNTHzTc387VPMDOxNk7k"
Server: Jetty(9.1.0.v20131115)

---
GET /combo?yui/cssgrids/cssgrids-min.css&yui/widget-base/assets/skins/sam/widget-base.css&... HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Cache-Control: max-age=0
Authorization: Basic YWRtaW46MTIz
Accept: text/css,*/*;q=0.1
If-None-Match: "1986623550"
If-Modified-Since: Tue, 23 Apr 2013 23:46:22 GMT
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 304 Not Modified
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,PUT,POST,DELETE,OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, Content-Length, X-Requested-With
Vary: Accept-Encoding
Last-Modified: Tue, 23 Apr 2013 23:46:22 GMT
Cache-Control: public,max-age=31536000
Expires: Fri, 16 Jan 2015 03:03:44 GMT
ETag: "1986623550"
Date: Thu, 16 Jan 2014 03:03:44 GMT
Connection: keep-alive

---
GET /combo?yui/oop/oop-min.js&yui/attribute-core/attribute-core-min.js&... HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Cache-Control: max-age=0
Authorization: Basic YWRtaW46MTIz
Accept: */*
If-None-Match: "1918884200"
If-Modified-Since: Thu, 02 May 2013 22:59:53 GMT
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 304 Not Modified
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,PUT,POST,DELETE,OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, Content-Length, X-Requested-With
Vary: Accept-Encoding
Last-Modified: Thu, 02 May 2013 22:59:53 GMT
Cache-Control: public,max-age=31536000
Expires: Fri, 16 Jan 2015 03:03:44 GMT
ETag: "1918884200"
Date: Thu, 16 Jan 2014 03:03:44 GMT
Connection: keep-alive

---
GET /combo?yui/dataschema-json/dataschema-json-min.js&yui/dataschema-xml/dataschema-xml-min.js&... HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Cache-Control: max-age=0
Authorization: Basic YWRtaW46MTIz
Accept: */*
If-None-Match: "1381642784"
If-Modified-Since: Tue, 23 Apr 2013 23:46:24 GMT
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

HTTP/1.1 304 Not Modified
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,PUT,POST,DELETE,OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, Content-Length, X-Requested-With
Vary: Accept-Encoding
Last-Modified: Tue, 23 Apr 2013 23:46:24 GMT
Cache-Control: public,max-age=31536000
Expires: Fri, 16 Jan 2015 03:03:45 GMT
ETag: "1381642784"
Date: Thu, 16 Jan 2014 03:03:45 GMT
Connection: keep-alive

---
GET /api/context HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Authorization: Basic YWRtaW46MTIz
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
X-Requested-With: XMLHttpRequest
Accept: */*
Referer: http://localhost:8000/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8
If-None-Match: "1217632044"

HTTP/1.1 304 Not Modified
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,PUT,POST,DELETE,OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, Content-Length, X-Requested-With
Vary: Accept-Encoding
ETag: "1217632044"
Date: Thu, 16 Jan 2014 03:03:46 GMT
Connection: keep-alive

---

编辑

我之所以提到 Chrome，是因为这是我正在使用的浏览器。其他浏览器的行为可能会有所不同，现在我对 Chrome 特别感兴趣。

【问题讨论】：

标签： html ajax caching cache-control

【解决方案1】：

它确实缓存了它们，但是每当您按下刷新按钮时，它都会强制重新验证所有资源。您会注意到它发送了If-None-Match 和If-Modified-Since 标头以便服务器可以有条件地响应，并且服务器发回304 指示缓存的副本仍然是新鲜的。我不确定为什么某些资源没有重新验证。

如果您想在不重新验证的情况下“重新加载”，只需选择 URL 栏并按 Enter。

【讨论】：